Spark-plug.



A. SCHMIDT.

SPARK PLUG.

I APPLICATI a. 1911. 1,283,572. Patented Nov. 5; 1918.

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ALBERT SCHMIDT, or FLINT, micmcnn, .essrcnon TQ centurion iem'rwn COMPANY,

. or FLINT, MioHIeen, .e. coaronnrlon' or senescence.

nesas'ra Specification oi Letters Patent.

Patented Nov, 5, 1918.

Application filed January 15, 1931?, serial No. 143,133- I To all whom it may concern H I Be it known that I, ALBERT So M D'r, a citizen of the Republic-of France, residing at Flint, in the county of Genesee and State 'particularly designed for use in high speed internal combustion motors, and it is the object of the invention to provide for the more rapid dissipation of the heat from the insulator. To this end the invention comprises, first, the means for maintaining mo lecular contact between the insulator and a body of relatively high heat conductivity; and further, various features of construction as hereinafter set forth.

In the drawings:

" Figure l is a longitudinal section through 4 a spark-plug having its insulator provided with a heat conducting jacket molecularly united thereto; Y. Fig. 2 is a similar view, showing a mod;- fied construction;

Fig. .8 is an enlarged section through the In the construction of spark-plugs, electrical insulation can only be obtained where there is exposure of the insulator to the flame of combustion. 0n the other hand, such exposure results in the heating of the insulator,

and as the lattgsr is usually a poor heat con- -ductor diflicul y is experienced in dissipating the heat with sullicient rapidity for high speed work. The slow rate of heat conduction is further due to the small amount of contact between the insulator and the metallic casing, this being usually limited to a scaling gasket With my improvement the heat conductivity of the insulator is greatly increased by covering a portion of its surface with a metal or other high heat con ducting substance which is in molecular contact with the insulating substance. This will provide a large contact area utor conducting the heat trom the insulating body to the heat-conducting body, while the latter will convey. the heat rapidly. to the point of contact with the external case In detail and as shown particularly in Fig. 1, A is an insulator and B is a surrounding metallic jacket in molecular contact therewith. The method of producing this molecular contact is preferably by electrolytic deposition, the surface of the insu-. lator being first rendered conductive by the chemical or mechanical deposit thereon of a thin film of conducting material, which is then coated electrolytically with a thick deposit of copper, silver or other metal high in heat conductivity. As shown in Fig. 1, the metallic jacket B surroundsthe enlargement C of the porcelain, extending over the shoulder D which is seated against the gashot E on the shoulder F of the surrounding casing G. The parts are held in this position by a flange H on the casing G, which is turned over an opposed shoulder I. With this construction the heat which is imparted is formed with a tapering inner end K, a nd.

the metallic jacket .iscarried over on to thetapering portion, as illustrated at B. The outer surface of the jacket may then be "machined or otherwise fashioned to exactly fit a corresponding shape in the metallic-casing G, so that the-jacket forms not only the heat-conducting medium but also the hearing or gasket which seals the insulator in the to the porcelain through the exposed surouter casing. This outer casing G is formed with a corresponding taper, and the insulator is provided with a sufficient exposure of surface at its inner end to maintain electrical insulation. The insulator may be retained: in the casing by turning over the flange H at the outer end in a similar manner to the construction shown in Fig. 1.

'With the plug constructed as described, the rate of heat dissipation from the insulator is largely increased over-any constructions heretofore devised, this being due primarily to the molecular contact of the insulator with the heat-conducting jacket and bein turthe'r due in the cohstruction shown in 2 to the large contact between this jacket and the metallic casing. Consequently the plug may be used for high-speed work with httle danger of a rise in temperature suiiicient tor preignition.

' coating. 1

2. In a spark-plug, an insulator, a metallie-electrolytic deposit in molecular contact With' a portion of the surface of said insulator and forming a body high in heat conductivity, and means for conducting the heat from said deposit to the casing of the plug.

3. In a spark-plug, the combination with the casin of an insulator, and a metallic electrolytically deposited coating in molecular contact with a portion of the surface of said insulator and in heat-conducting contact with said casing.

heat conductivity, said deposit being in.

heat conducting contact With said casing. 5. In a spark-plug, the combination of an insulator having a central enlargement and a tapering portion therefrom to the inner end, of a surrounding jacket of electrolytically deposited metal extending over said enlargement and a portion of the taper of the insulator and being in molecular contact therewith, and a casing of corresponding form in contact with said jacket and clamped thereto.

In testimony whereof I afiix my signature.

ALBERT SCHMIDT. 

